POS1389 SUGGESTION OF OPTICAL SPECTRAL TRANSMISSION IMAGING (HandScan) CUT-OFF VALUES IN PATIENTS WITH RHEUMATOID ARTHRITIS AND CORRELATIONS WITH CLINICAL AND LABORATORY DISEASE ACTIVITY MARKERS.
Authors: K. Triantafyllias, K. Altamimi, M. De Blasi, A. Schwarting
Journal: Annals of the Rheumatic Diseases (2022)

Background Optical spectral transmission (OST) is a modern diagnostic modality able to assess the blood-specific absorption of light transmitted through a tissue, promising quantification of inflammation in the finger and wrist joints of patients with rheumatoid arthritis (RA) (HandScan -Demcon/Hemics, The Netherlands). Early data on OST revealed both correlations with clinical and arthrosonographic activity markers of RA, as well as a high diagnostic value during disease follow-up [1-3]. However, in a previous work we could detect and describe several OST confounding factors that complicate the establishment of universal cut-off values [2]. Objectives Aim of this study was to examine and suggest OST-cut-off values after adjusting for the effect of statistically identified confounding factors. Moreover, we sought to describe a clinical model that would represent the probability of a positive RA diagnosis on the basis of OST values and presence of confounders in every individual patient. Methods Newly diagnosed RA patients (ACR-EULAR Classification Criteria 2010) were examined by OST and compared with healthy controls. Moreover, RA patients underwent clinical (tender &amp; swollen joint counts, DAS28) and laboratory (inflammation markers) examinations. To identify factors that could have a confounding effect on OST, we performed logistic multivariate regression analyses, taking into account patient-associated characteristics such as age, gender, BMI, hand size, nicotine use. After identifying confounders, we determined OST cut-offs for different patient categories. In addition, we calculated the probability of the presence of an RA-diagnosis, based on the measured OST value and the presence of the identified influencing factors. Finally, we examined correlations of OST with clinical and laboratory RA activity parameters. Results 74 early RA patients [64%♀; median age 59 years (53-70, IQR); median DAS28 4.58 (3.5-5.3, IQR)] and 101 controls [80%♀; median age 45 years (35-56, IQR)] were recruited. Male gender and advanced age were statistically identified as OST influencing factors. Receiver operating characteristics (patients vs. controls) revealed an OST cut-off value of 11.2 (sensitivity 85%, specificity 72%) for female and an OST cut-off of 16.07 (sensitivity 75.7%, specificity 72.7%) for male patients. Two models were shown to be statistically appropriate for calculating the probability of the presence of RA based on the measured OST values and confounders: one model with included age for females and one model with included age and smoking status for males (Table 1). Table 1. Statistical models for calculating the probability of the presence of rheumatoid arthritis based on measured OST values and OST confounding factors. Statistical model Women Men OST: optical spectral transmission; P(RA): probability of RA diagnosis X1 for age, X2 for OST; X3 for nicotine use OST showed statistically significant moderate correlations with DAS28 (r=0.42, p&lt;0.001), swollen joint count (r=0.437, p&lt;0.001), VAS (r=0.355, p=0.002) and a weak significant correlation with CRP (r=0.23, p=0.045). Conclusion The establishment of OST cut-off values adjusted for confounding factors and the suggested statistical models could contribute to an increase of the diagnostic value of HandScan and assist clinicians during patient screening. To our knowledge, this is the first report in the literature on the specific topic. Further patient recruitment and research regarding additional confounders are currently taking place with the aim of improving the diagnostic capabilities of this new and promising diagnostic technology. References [1]van Onna M, et al. Ann Rheum Dis. 2016;75(3):511-8. [2]Triantafyllias K, et al. J Rheum. 2020;47(9):1314-22. [3]Triantafyllias K, et al. Ann Rheum Dis. 2020;79(Suppl 1):1244.1 Disclosure of Interests None declared